Question Number 106559 by MessiasAntonii last updated on 05/Aug/20
$${sen}\left(\mathrm{7}\right)= \\ $$
Commented by bobhans last updated on 06/Aug/20
$$\mathrm{cos}\:\left(\mathrm{14}°\right)=\mathrm{1}−\mathrm{2sin}\:^{\mathrm{2}} \left(\mathrm{7}°\right) \\ $$$$\mathrm{sin}\:\left(\mathrm{7}°\right)=\sqrt{\frac{\mathrm{1}−\mathrm{cos}\:\left(\mathrm{14}°\right)}{\mathrm{2}}}\:\smile\overset{\bullet} {\bullet}\smile \\ $$